Scientific Reading Comprehension Flashcards

A passage explains that a study used a 'washout period' of two weeks between treatment phases in a crossover design. The purpose of the washout period is to:

Answer: Allow effects of the first treatment to dissipate before starting the second treatment

Washout periods in crossover designs prevent carryover effects from the first intervention influencing outcomes in the second phase.

A passage presents data showing that 8 out of 100 patients in the treatment group developed dry eye versus 16 out of 100 in the control group. The relative risk reduction is:

Answer: 50%

RRR = (control rate - treatment rate) / control rate = (0.16 - 0.08) / 0.16 = 0.50 = 50%.

A passage describes a cross-sectional study measuring refractive error and screen time in 1,000 adolescents at a single point in time. A major limitation of this design for establishing causality is:

Answer: Temporal sequence cannot be established—it is unknown whether screen time preceded myopia

Cross-sectional studies measure exposure and outcome simultaneously, making it impossible to determine which came first.

A passage notes that after controlling for age, sex, and IOP, the association between corneal hysteresis and glaucoma progression remained significant (OR = 1.8, 95% CI: 1.2–2.6). The fact that CI does not include 1.0 indicates:

Answer: The odds ratio is statistically significant at the 0.05 level

For an odds ratio, a 95% CI that excludes 1.0 indicates statistical significance because 1.0 represents no association.

A passage uses the phrase 'the data suggest' rather than 'the data prove.' This language choice reflects:

Answer: Appropriate scientific caution acknowledging that findings support but do not definitively establish conclusions

Scientific writing uses hedging language like 'suggest' to reflect the probabilistic and provisional nature of empirical evidence.

A passage describes a multivariate regression analysis in which visual acuity is the dependent variable. Including multiple independent variables (age, IOP, corneal thickness) in the model primarily allows researchers to:

Answer: Estimate the independent effect of each variable while holding the others constant

Multivariate regression isolates each variable's contribution by statistically controlling for the effects of all other included variables.

A passage presents a scatter plot with a best-fit line showing R² = 0.62 between hours of outdoor activity and axial length. The R² value indicates that:

Answer: 62% of the variance in axial length is explained by hours of outdoor activity

R² (coefficient of determination) represents the proportion of variance in the outcome explained by the predictor variable.